Current-collecting device



April 1 1924. I 1,488,574

C. F. WAGNER Filed July 5, 1922 Fig.3. I

WITNESSES: Ch FITNQIAE/EITOR qr es asner.

ATTORNEY Patented Apr. 1, 1924.

PATENT, OFFICE.

owns 1'. WAGNER, or rrr'rsnunen, PENNSYLVANIA, ASSIGN'OR T wns'rmop HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION or PENNSYL- vmm.

CURRENT-COLLECTING DEVICE.

I! '0 all whom it may concern:

Be it known that LCHARLEs F. lVAeNnn,

a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Current Collecting Devices, of which the following is a specification.

My invention relates to current-collecting devices and it has particular relation to means for equalizing the current traversing the several brushes of a dynamo-electric machine.

Heretofore, it has been observed that the current-collecting brushes of dynamo-electric machines, and particularly machines of the rotary converter type which employ a large number of brushes connected in parallel relation and which co-operate with a'single collector ring, are subjected to unequal wear. Extensive experiments have, therefore, been conducted with a view to determine the cause of the inequality in brush wear. As a result of such investigations, it has been ascertained that one of the principal causes of the unequal brush wear is the unequal flow of current through the several brush members which causes the decomposition of the brushes subjected to excess current flow. The inequality of current flow in the different brushesmay, in turn, be attributed to several causes, such as the forma tion of a film of air, of substantially wedge shape, between the brush member and the :55 collector ring; carbon deposits on the contact surfaces of certain of the brushes; un equal pressures exerted by the brush springs;

I uneven contact surfaces of the brushv members; inequalities in the chemical constituents of the contactsurfaces, and particularly those of the brush members; the unstable volt-ampere characteristics of the brushes in general and the effect of nonuniform external conditions, such as the resistances and the reactanees of the paths of the current from the brushes, as in the brush-holder stand to which the brush shunts are electrically connected.

One of the objects of my invention is to provide means for overcoming the difference in impedance existin in the current paths of a plurality of brus es connected in parallel relation and to stabilize or balance the current flow therethrough.

Another object of my invention is to provide a device, of the character described, that may be quickly and easily connected in the brush circuits of a dynamo-electric machine without changing the structure thereof and. that may be employed in connection with machines of standard structure withoutmaterially increasing the cost thereof. In the accompanying drawing,

Fig.1 is a plan view of a brush holder of standard construction provided with a laminated core member having a winding electromagnetically associated therewith which is adapted to insert reactance in the path of the current from the brush.

Fig. 2 is aside elevational view of the structure illustrated in Fig. 1;

. Fig. 3 is a diagrammatic view of aportion of a collector ring having a plurality of brush members cooperating therewith and which are provided with core members for inserting reactance in seriestherewith.

Referring to the drawing, a brush holder of standard construction is shown as comprising a brush box 1 which is adapted to receive and retain a brush member 2 for co-operation with a. collector ring 3. The brush box 1 is provided with a vertically extending portion a which is secured to a bracket 5 by means of a bolt 6. The bracket 5 is mounted upon a stud 7 which is secured to the frame of the machine, not shown. The portion 4 of the brush holder is provided with a serrated surface 8 which c-oact-s with a similarly formed surface of the bracket 5 and by means of which the brush box is positively maintained in adjusted position relative to the collector ring 3.

The brush box 1 is insulated from the bracket 5 by means of a relatively thin flexible strip 9 of insulating material which is clamped between the serrated surfaces 8 thereof and also by means of an insulating washer 1O disposed between the head of the bolt 6 and the outer surface of the portion 4.

The upper extremity of the bracket 5 is provided with a lug 11 to which a laminated core member 12 is secured by means of screws 13. The core member 12 may be provided with an air gap 14, if so desired. A winding 15 embraces one of the legs of the core member 12 and is secured, at one end, to the lug 11 of the bracket 5 at 16. The other extremity of the winding 15 is formed with an eye portion 17 to which a plurality of brush shunts 18 are secured by means of a transversely extending bolt 19 and spacing member 20.

By means of the above described construction, it an excessive current tends to flow through any one of the several brushes by reason of any of the conditions hercinbeitore set forth, the magnetic field, comprising the core member 12, is correspondingly strengthened to generate an increased e-lectromotive force that opposes the flow of current through the winding 15. The result is, therefore, to increase the impedance of the current of low resistance approximately in proportion to the value of the current traversing it. The tendency of the several resistors is, accordingly, to equalize or balance the flow of current through the various paths, and the disadvantageous effects of excessive current flowing in any one of the branches is thereby avoided.

I claim as my invention:

1. A. current-collecting device comprising a brush holder adapted to support a brush member for co-operation with a rotating contact member and a core member mounted on said brush holder and adapted to insert a reactance in the path of the current through said brush.

2. A current-collecting device comprising a brush holder, a brush member carried thereby for co-operation with a rotating contact member, a core member carried by said brush holder, a winding electromagneti rally associated with said core member and connected in series with said brush.

3. A current-collecting device comprising a brush holder carried thereby for co-operation with a rotating contact member, a lam- A current-collecting device comprising L a brush holder, a. brush carried thereby for co-operation with a rotating contact member, said brush holder being provided with a vertically extending lug, a core member of substantially C shape and having its extremities secured to said lug, and awinding olectromagnetically associated with one of the legs of said core member and having its respective ends electrically connected to said brush member and to said lug.

In testimony whereof, I have hereunto subscribed my name this 28th day of June, 1922.

CHARLES F. VAGNER. 

